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Integration
Configuring the Unit Controller
Each MicroTech II Unit Controller board and N2 communication module is preprogrammed and
configured at the factory to be a single Unit Controller, whether the boards are assembled together at
the factory or field assembled. Each unit is also ready to operate using the default values. These
default values may be changed via the unit's keypad, using ServiceTools™, or via the network. See
the appropriate operation manual for default values and keypad operating instructions, and refer to
the appropriate MicroTech II Protocol Information for descriptions of the network variables. See
Reference Documents for part numbers.
Network Connection
N2 Open Addressing
The N2 Open device address of the MicroTech II controller in a Local Area Network (LAN) is set by
using the eight-position DIP switch on the N2 communication module (see the heading: Address
Switch). The address is physically set using the binary switches. An open switch (switch up) is a 0,
and the value of a closed switch (switch down) is shown in Figure 4. The address naming starts with
switch 1. Each address must be unique and set during installation. After setting the address with the
switches, you must cycle power to the controller (turn the controller off and then on again) for the
new address to take effect.
The data transmission rate is 9600-bps (baud)..
N2 Bus Information
The N2 communication Bus is a local network that links controllers and point interfaces to the
Network Control module (NCM). The N2 Bus uses a master/slave protocol in which the master
device (the NCM) initiates all communication with the N2 Bus devices. These N2 Bus devices
include the Digital Control modules (DCMs), Point Multiplex modules (XBN, XRE, XRL, XRM),
and all Application Specific Controllers (ASCs).
The N2 Bus is wired in a daisy-chain fashion and the devices are connected in series. The N2 Bus
can use solid or stranded wire, or optical fiber when special fiber modems are used. So the choices
include:
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Selecting the Right Cable
For most N2 Bus installations, the most practical choice is solid, 2-wire twisted-pair, unshielded,
telephone cables. If you have existing stranded cable, you can use it, but you may find that the
strands become a nuisance when wiring the cable.
For N2 Bus installations where there is a lot of electrical noise (e.g., gas ignition systems, radar or
magnetic-resonance imaging equipment, on a factory floor, or outdoors), shielded wire or optical
fiber is the best choice. Of the two, fiber is by far the better option, but it is more expensive. It offers
extended N2 distances and excellent immunity to electrical noise, lightning, and various other
building noises. It can also be buried underground between two buildings so that the N2 Bus can be
extended in a campus-type installation.
IM 730-0
3-wire twisted cable
2-wire twisted-pair telephone cable
2-wire twisted-pair cable with a shield
Duplex optical fiber (requires a pair of fiber modems).
7
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